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CloudFlare describes Rocket Loader like this...
Rocket Loader is a general-purpose asynchronous JavaScript loader
coupled with a lightweight virtual browser which can safely run any
JavaScript code after window.onload.
Rocket Loader does a bunch of things:
It ensures that all the scripts on your page will not block the content of your ...

Sure. Obviously, it would be better to use CSS alone but if you can't, use what you have. Do as much as you can with CSS and use JS as needed. Not sure why you can't change the existing CSS but you can add a style sheet with JS.
(function() {
//create a new element
var newStyle = document.createElement("link");
//set the required attribute for a ...

Nice question, here are some guides for doing that on that level.
1. CRAWL YOUR SITE
When you redesign your website, there’s a good chance that URLs will change. If URLs change, you absolutely have to inform the engines where those older URLs have moved to. If you don’t, you can destroy your SEO power. All of the equity those old URLs have built up can ...

The CDN should be used for all static files (.css/.js/images).
Sometimes however javascript or css files can have dynamic aspect to them such as that it would include a unique user string or something of that sort. In this situation the CDN server would have to contact the origin server on every request which would defeat the purpose.
If your CSS and ...

You have no control over them because they are hosted by another provider. And honestly speaking you should not worry about them, it's up to Google, Facebook, etc to handle the caching accordingly to their need.
You could potentially proxy the URLs or download the files locally, but I don't encourage you to follow that route. In fact, you may potentially ...

Well its not your site, its China's internet service layout, which has to jump through hoops to get even get to US DNS Servers. Furthermore, I don't know how 'free' the Internet surfing is there, meaning if it's being monitored by the government, which would undoubtedly further slow its response times. Many factors can be attributed to your site being slow ...

This is a design limitation:
The file size must be between 1,000 and 10,000,000 bytes.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/ServingCompressedFiles.html
Compressing files is resource-intensive, so the designers of CloudFront placed an upper bound on the size of files that CloudFront will spend resources compressing on-...

the other 4 are only used for a word or two
Is that a literal statement?
If so why are you bothering to embed these fonts at all, subsets or not? You shouldn't even be optimizing in this case, just removing. Make images of the text you need and use your favorite text-replacement technique. You're adding HTTP requests and download time to your site for the ...

Based on your reference to the ImageMagick convert method and quality parameter, it appears you're working with JPEG images. If that's the case, the EXIF information for JPEG images does not have a standard compression level tag.
However, ImageMagick appears to be able to obtain this information from the image's quantization tables using the identify ...

Adding the height and width attributes to your IMG SRC HTML tag allows
the browser to know how much space to leave for an image. Without
these values, the browser gives an image no space until the image is
loaded, which means anything surrounding the image is adjusted after
the image has loaded.
http://www.computerhope.com/issues/ch001158.htm

In addition to post-launch actions, I don't think you should completely ignore what's already there. You're speaking in future tense, so I presume the new site isn't ready yet; use that to your advantage and do a bit of tidying before you even make the switch.
If you have pages that will have a replacement (to which you'll want a 301 redirect) then take a ...

I don't think the modern search engines care about "older" phone compatibility. If the site is mobile-friendly in modern terms, the spiders will detect that and search engines that report it, will.
I suppose you could waste your meta description and/or the opening sentence of text on the site to declare that you are backwards compatible with Nokia flip ...

This heavily depends on the target of the audience.
For developers, I would offer a Login via Github. For all other matters, having a sign in via Facebook AND Twitter would not hurt.
What my company tough observed was, that even tough we are offering the login via Twitter and Facebook, 95% of the Users just sign in via a regular new account.

Enter that website's url into www.opensiteexplorer.org (or any other backlink checker) and you'll see it has lots of backlinks from a variety of domains.
You can further use other toolboxes (sistrix, searchmetrics, xovi, seolytics...) to analyze the value of the site over a period of time to see if there was a sudden spike of links or if the link building ...

Assuming the HTML page is of a reasonable size (back in 2006 it was 500kb, now it's likely much more), Google doesn't care about your pages' text-to-code ratio. Focus on creating great content instead, don't worry about your markup from an SEO point of view.
From a user's point of view, having a fast-loading page is great (so take care of unnecessary fluff,...

I would say try using media queries first. One method I found easier when dealing with a design that was originally only for desktop was this:
Start with two separate stylesheets. One for the new responsive design, and the other for the old desktop version:
<link rel="stylesheet" media="screen and (max-width: 959px)" href="css/mobile.css">
<link ...

Unfortunately, you most probably won't be capable of measuring the SEO performance of the page before and after on-page optimization. The reason is you can't freeze the search engines for a period of time for your keywords. Search engines continue to calculate positions during the time where robots (web crawlers) index your page page for the first time and ...

When I want to do SEO changes and measure the results, I change half the pages on the site. This works best if you have a site with lots of similar pages that get similar amounts of search engine traffic. To make it work:
Divide your pages into two groups, randomly if possible. I generally use the content id for each page and do even and odd.
Exclude ...

Google is attempting to append your site name to your title. Most sites put the site name at the end of titles themselves because:
It is good for branding
It differentiates your listing in the search results and makes users more likely to click
Its better at the end of the title than at the beginning because having the site name get truncated isn't a big ...

Yes, if load time is lower, you will have optimised the page. Also, the font file will be cached after the first request, so you will most likely end up with only a single request for the font file.
To verify, you could use your browser's built-in timeline, or use an external tool like Google PageSpeed Insights: https://developers.google.com/speed/pagespeed/...

The browser requests this for performance. Say you have a paragraph of text with an image of 100x100 pixels in the top left corner.
Browser builds the page, no image yet, so it builds it with just text
The image now loads, and suddenly there's space needed
Browser rebuilds the page, with the proper room for the image
If you give width and height to the ...

If duplicating the image really is unnecessary then you could still perhaps have the best of both worlds... only store the image once, but have it referenced by different filenames, for the different languages - using mod_rewrite (Apache) and an internal rewrite.
Based on unor's example:
example.net/img/en/house.png
example.net/img/es/casa.png
These would ...

TTFB is totally dependent on server load and available bandwidth.
If your server is heavily loaded (lots of requests per second) then your TTFB will rise exponentially. This effect is multiplied by lower server spec and available bandwidth.
Spreading the load over multiple sub domains may or may not have any effect, this depends on how you actually ...

Adding MORE (sub)domains can only INCREASE this value because the computer/visitor has to do another lookup to resolve the domain to an IP.
You'd be better off trying to find out WHY you have a high TTFB.
From Wikipedia: "Time To First Byte or TTFB is a measurement that is often used as an indication of the responsiveness of a webserver or other network ...

Using non-standard web fonts have a significant performance impact on page load times compared to just using standard web-safe system fonts. This is the case regardless of whether you're using JavaScript or @font-face.
One should always carefully analyze whether or not non-standard web fonts should be used.
Some questions to ask yourself when considering ...

You'll need to mix high resolution graphics, css and things like @font-face, obviously if you create a website specifically for retina displays it will create a lot of data to download with larger images etc, but what you can do is using CSS create optimised verstions for retina and non-retina visitors.
There are some great tutorials online including these:
...

If the posts on the other site are already indexed in search engines, you might just consider linking back to your main site, or doing 301 redirects to it. If you duplicate the posts on your main site, you're going to have duplicate content issues, which can be managed through Canonicalization.
In regards to pages versus posts, posts are better organized ...

This method of deploying a newer version of a prior established website to a different domain is very much flawed as you've probably come to realize now from comments and posts above, mainly relating to the issues of Page Rank effect of aged domain and index history, the duplicate content issue and the 301 redirects.
I would strongly recommend your next ...

I worked on a site that used that method, and I had problems with screen rotation on mobile devices. Since JavaScript will only detect once on page load, if the user rotates the device it won't expand to the full width the way it will with media queries. It was easier for me at the time just to switch to CSS, but perhaps a JS expert would know if there's a ...